[media] uvcvideo: Set error_idx properly for S_EXT_CTRLS failures

pinchartl · Mauro Carvalho Chehab · commit 68d6f84ba0c4 · 2013-01-11T13:30:27.000-02:00
The uvc_set_ctrl() calls don't write to the hardware. A failure at that
point thus leaves the device in a clean state, with no control modified.
Set the error_idx field to the count value to reflect that, as per the
V4L2 specification.
TRY_EXT_CTRLS is unchanged and the error_idx field must always be set to
the failed control index in that case.

Signed-off-by: Laurent Pinchart &lt;laurent.pinchart@ideasonboard.com&gt;
Acked-by: Hans Verkuil &lt;hans.verkuil@cisco.com&gt;
Signed-off-by: Mauro Carvalho Chehab &lt;mchehab@redhat.com&gt;
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -685,7 +685,8 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 			ret = uvc_ctrl_set(chain, ctrl);
 			if (ret < 0) {
 				uvc_ctrl_rollback(handle);
-				ctrls->error_idx = i;
+				ctrls->error_idx = cmd == VIDIOC_S_EXT_CTRLS
+						 ? ctrls->count : i;
 				return ret;
 			}
 		}

Original file line number	Diff line number	Diff line change
`@@ -685,7 +685,8 @@ static long uvc_v4l2_do_ioctl(struct file file, unsigned int cmd, void arg)`
`685`	`685`	`ret = uvc_ctrl_set(chain, ctrl);`
`686`	`686`	`if (ret < 0) {`
`687`	`687`	`uvc_ctrl_rollback(handle);`
`688`		`- ctrls->error_idx = i;`
	`688`	`+ ctrls->error_idx = cmd == VIDIOC_S_EXT_CTRLS`
	`689`	`+ ? ctrls->count : i;`
`689`	`690`	`return ret;`
`690`	`691`	`}`
`691`	`692`	`}`